/* ***************************************************************************
 *
 * ftmodapi.h
 *
 * FreeType modules public interface (specification).
 *
 * Copyright (C) 1996-2021 by
 * David Turner, Robert Wilhelm, and Werner Lemberg.
 *
 * This file is part of the FreeType project, and may only be used,
 * modified, and distributed under the terms of the FreeType project
 * license, LICENSE.TXT.  By continuing to use, modify, or distribute
 * this file you indicate that you have read the license and
 * understand and accept it fully.
 *
 */


#ifndef FTMODAPI_H_
#define FTMODAPI_H_


#include <freetype/freetype.h>

#ifdef FREETYPE_H
#error "freetype.h of FreeType 1 has been loaded!"
#error "Please fix the directory search order for header files"
#error "so that freetype.h of FreeType 2 is found first."
#endif


FT_BEGIN_HEADER


/* *************************************************************************
 *
 * @section:
 * module_management
 *
 * @title:
 * Module Management
 *
 * @abstract:
 * How to add, upgrade, remove, and control modules from FreeType.
 *
 * @description:
 * The definitions below are used to manage modules within FreeType.
 * Internal and external modules can be added, upgraded, and removed at
 * runtime.  For example, an alternative renderer or proprietary font
 * driver can be registered and prioritized.  Additionally, some module
 * properties can also be controlled.
 *
 * Here is a list of existing values of the `module_name` field in the
 * @FT_Module_Class structure.
 *
 * ```
 * autofitter
 * bdf
 * cff
 * gxvalid
 * otvalid
 * pcf
 * pfr
 * psaux
 * pshinter
 * psnames
 * raster1
 * sfnt
 * smooth
 * truetype
 * type1
 * type42
 * t1cid
 * winfonts
 * ```
 *
 * Note that the FreeType Cache sub-system is not a FreeType module.
 *
 * @order:
 * FT_Module
 * FT_Module_Constructor
 * FT_Module_Destructor
 * FT_Module_Requester
 * FT_Module_Class
 *
 * FT_Add_Module
 * FT_Get_Module
 * FT_Remove_Module
 * FT_Add_Default_Modules
 *
 * FT_FACE_DRIVER_NAME
 * FT_Property_Set
 * FT_Property_Get
 * FT_Set_Default_Properties
 *
 * FT_New_Library
 * FT_Done_Library
 * FT_Reference_Library
 *
 * FT_Renderer
 * FT_Renderer_Class
 *
 * FT_Get_Renderer
 * FT_Set_Renderer
 *
 * FT_Set_Debug_Hook
 *
 */


/* module bit flags */
#define FT_MODULE_FONT_DRIVER 1 /* this module is a font driver  */
#define FT_MODULE_RENDERER 2    /* this module is a renderer     */
#define FT_MODULE_HINTER 4      /* this module is a glyph hinter */
#define FT_MODULE_STYLER 8      /* this module is a styler       */

#define FT_MODULE_DRIVER_SCALABLE 0x100      /* the driver supports      */
                                             /* scalable fonts           */
#define FT_MODULE_DRIVER_NO_OUTLINES 0x200   /* the driver does not      */
                                             /* support vector outlines  */
#define FT_MODULE_DRIVER_HAS_HINTER 0x400    /* the driver provides its  */
                                             /* own hinter               */
#define FT_MODULE_DRIVER_HINTS_LIGHTLY 0x800 /* the driver's hinter      */
                                             /* produces LIGHT hints     */


/* deprecated values */
#define ft_module_font_driver FT_MODULE_FONT_DRIVER
#define ft_module_renderer FT_MODULE_RENDERER
#define ft_module_hinter FT_MODULE_HINTER
#define ft_module_styler FT_MODULE_STYLER

#define ft_module_driver_scalable FT_MODULE_DRIVER_SCALABLE
#define ft_module_driver_no_outlines FT_MODULE_DRIVER_NO_OUTLINES
#define ft_module_driver_has_hinter FT_MODULE_DRIVER_HAS_HINTER
#define ft_module_driver_hints_lightly FT_MODULE_DRIVER_HINTS_LIGHTLY


typedef FT_Pointer FT_Module_Interface;


/* *************************************************************************
 *
 * @functype:
 * FT_Module_Constructor
 *
 * @description:
 * A function used to initialize (not create) a new module object.
 *
 * @input:
 * module ::
 * The module to initialize.
 */
typedef FT_Error (*FT_Module_Constructor)(FT_Module module);


/* *************************************************************************
 *
 * @functype:
 * FT_Module_Destructor
 *
 * @description:
 * A function used to finalize (not destroy) a given module object.
 *
 * @input:
 * module ::
 * The module to finalize.
 */
typedef void (*FT_Module_Destructor)(FT_Module module);


/* *************************************************************************
 *
 * @functype:
 * FT_Module_Requester
 *
 * @description:
 * A function used to query a given module for a specific interface.
 *
 * @input:
 * module ::
 * The module to be searched.
 *
 * name ::
 * The name of the interface in the module.
 */
typedef FT_Module_Interface (*FT_Module_Requester)(FT_Module module, const char *name);


/* *************************************************************************
 *
 * @struct:
 * FT_Module_Class
 *
 * @description:
 * The module class descriptor.  While being a public structure necessary
 * for FreeType's module bookkeeping, most of the fields are essentially
 * internal, not to be used directly by an application.
 *
 * @fields:
 * module_flags ::
 * Bit flags describing the module.
 *
 * module_size ::
 * The size of one module object/instance in bytes.
 *
 * module_name ::
 * The name of the module.
 *
 * module_version ::
 * The version, as a 16.16 fixed number (major.minor).
 *
 * module_requires ::
 * The version of FreeType this module requires, as a 16.16 fixed
 * number (major.minor).  Starts at version 2.0, i.e., 0x20000.
 *
 * module_interface ::
 * A typeless pointer to a structure (which varies between different
 * modules) that holds the module's interface functions.  This is
 * essentially what `get_interface` returns.
 *
 * module_init ::
 * The initializing function.
 *
 * module_done ::
 * The finalizing function.
 *
 * get_interface ::
 * The interface requesting function.
 */
typedef struct FT_Module_Class_ {
    FT_ULong module_flags;
    FT_Long module_size;
    const FT_String *module_name;
    FT_Fixed module_version;
    FT_Fixed module_requires;

    const void *module_interface;

    FT_Module_Constructor module_init;
    FT_Module_Destructor module_done;
    FT_Module_Requester get_interface;
} FT_Module_Class;


/* *************************************************************************
 *
 * @function:
 * FT_Add_Module
 *
 * @description:
 * Add a new module to a given library instance.
 *
 * @inout:
 * library ::
 * A handle to the library object.
 *
 * @input:
 * clazz ::
 * A pointer to class descriptor for the module.
 *
 * @return:
 * FreeType error code.  0~means success.
 *
 * @note:
 * An error will be returned if a module already exists by that name, or
 * if the module requires a version of FreeType that is too great.
 */
FT_EXPORT(FT_Error)
FT_Add_Module(FT_Library library, const FT_Module_Class *clazz);


/* *************************************************************************
 *
 * @function:
 * FT_Get_Module
 *
 * @description:
 * Find a module by its name.
 *
 * @input:
 * library ::
 * A handle to the library object.
 *
 * module_name ::
 * The module's name (as an ASCII string).
 *
 * @return:
 * A module handle.  0~if none was found.
 *
 * @note:
 * FreeType's internal modules aren't documented very well, and you
 * should look up the source code for details.
 */
FT_EXPORT(FT_Module)
FT_Get_Module(FT_Library library, const char *module_name);


/* *************************************************************************
 *
 * @function:
 * FT_Remove_Module
 *
 * @description:
 * Remove a given module from a library instance.
 *
 * @inout:
 * library ::
 * A handle to a library object.
 *
 * @input:
 * module ::
 * A handle to a module object.
 *
 * @return:
 * FreeType error code.  0~means success.
 *
 * @note:
 * The module object is destroyed by the function in case of success.
 */
FT_EXPORT(FT_Error)
FT_Remove_Module(FT_Library library, FT_Module module);


/* *************************************************************************
 *
 * @macro:
 * FT_FACE_DRIVER_NAME
 *
 * @description:
 * A macro that retrieves the name of a font driver from a face object.
 *
 * @note:
 * The font driver name is a valid `module_name` for @FT_Property_Set
 * and @FT_Property_Get.  This is not the same as @FT_Get_Font_Format.
 *
 * @since:
 * 2.11
 *
 */
#define FT_FACE_DRIVER_NAME(face) ((*FT_REINTERPRET_CAST(FT_Module_Class **, (face)->driver))->module_name)


/* *************************************************************************
 *
 * @function:
 * FT_Property_Set
 *
 * @description:
 * Set a property for a given module.
 *
 * @input:
 * library ::
 * A handle to the library the module is part of.
 *
 * module_name ::
 * The module name.
 *
 * property_name ::
 * The property name.  Properties are described in section
 * @properties.
 *
 * Note that only a few modules have properties.
 *
 * value ::
 * A generic pointer to a variable or structure that gives the new
 * value of the property.  The exact definition of `value` is
 * dependent on the property; see section @properties.
 *
 * @return:
 * FreeType error code.  0~means success.
 *
 * @note:
 * If `module_name` isn't a valid module name, or `property_name`
 * doesn't specify a valid property, or if `value` doesn't represent a
 * valid value for the given property, an error is returned.
 *
 * The following example sets property 'bar' (a simple integer) in
 * module 'foo' to value~1.
 *
 * ```
 * FT_UInt  bar;
 *
 *
 * bar = 1;
 * FT_Property_Set( library, "foo", "bar", &bar );
 * ```
 *
 * Note that the FreeType Cache sub-system doesn't recognize module
 * property changes.  To avoid glyph lookup confusion within the cache
 * you should call @FTC_Manager_Reset to completely flush the cache if a
 * module property gets changed after @FTC_Manager_New has been called.
 *
 * It is not possible to set properties of the FreeType Cache sub-system
 * itself with FT_Property_Set; use @FTC_Property_Set instead.
 *
 * @since:
 * 2.4.11
 *
 */
FT_EXPORT(FT_Error)
FT_Property_Set(FT_Library library, const FT_String *module_name, const FT_String *property_name, const void *value);


/* *************************************************************************
 *
 * @function:
 * FT_Property_Get
 *
 * @description:
 * Get a module's property value.
 *
 * @input:
 * library ::
 * A handle to the library the module is part of.
 *
 * module_name ::
 * The module name.
 *
 * property_name ::
 * The property name.  Properties are described in section
 * @properties.
 *
 * @inout:
 * value ::
 * A generic pointer to a variable or structure that gives the value
 * of the property.  The exact definition of `value` is dependent on
 * the property; see section @properties.
 *
 * @return:
 * FreeType error code.  0~means success.
 *
 * @note:
 * If `module_name` isn't a valid module name, or `property_name`
 * doesn't specify a valid property, or if `value` doesn't represent a
 * valid value for the given property, an error is returned.
 *
 * The following example gets property 'baz' (a range) in module 'foo'.
 *
 * ```
 * typedef  range_
 * {
 * FT_Int32  min;
 * FT_Int32  max;
 *
 * } range;
 *
 * range  baz;
 *
 *
 * FT_Property_Get( library, "foo", "baz", &baz );
 * ```
 *
 * It is not possible to retrieve properties of the FreeType Cache
 * sub-system with FT_Property_Get; use @FTC_Property_Get instead.
 *
 * @since:
 * 2.4.11
 *
 */
FT_EXPORT(FT_Error)
FT_Property_Get(FT_Library library, const FT_String *module_name, const FT_String *property_name, void *value);


/* *************************************************************************
 *
 * @function:
 * FT_Set_Default_Properties
 *
 * @description:
 * If compilation option `FT_CONFIG_OPTION_ENVIRONMENT_PROPERTIES` is
 * set, this function reads the `FREETYPE_PROPERTIES` environment
 * variable to control driver properties.  See section @properties for
 * more.
 *
 * If the compilation option is not set, this function does nothing.
 *
 * `FREETYPE_PROPERTIES` has the following syntax form (broken here into
 * multiple lines for better readability).
 *
 * ```
 * <optional whitespace>
 * <module-name1> ':'
 * <property-name1> '=' <property-value1>
 * <whitespace>
 * <module-name2> ':'
 * <property-name2> '=' <property-value2>
 * ...
 * ```
 *
 * Example:
 *
 * ```
 * FREETYPE_PROPERTIES=truetype:interpreter-version=35 \
 * cff:no-stem-darkening=0
 * ```
 *
 * @inout:
 * library ::
 * A handle to a new library object.
 *
 * @since:
 * 2.8
 */
FT_EXPORT(void)
FT_Set_Default_Properties(FT_Library library);


/* *************************************************************************
 *
 * @function:
 * FT_Reference_Library
 *
 * @description:
 * A counter gets initialized to~1 at the time an @FT_Library structure
 * is created.  This function increments the counter.  @FT_Done_Library
 * then only destroys a library if the counter is~1, otherwise it simply
 * decrements the counter.
 *
 * This function helps in managing life-cycles of structures that
 * reference @FT_Library objects.
 *
 * @input:
 * library ::
 * A handle to a target library object.
 *
 * @return:
 * FreeType error code.  0~means success.
 *
 * @since:
 * 2.4.2
 */
FT_EXPORT(FT_Error)
FT_Reference_Library(FT_Library library);


/* *************************************************************************
 *
 * @function:
 * FT_New_Library
 *
 * @description:
 * This function is used to create a new FreeType library instance from a
 * given memory object.  It is thus possible to use libraries with
 * distinct memory allocators within the same program.  Note, however,
 * that the used @FT_Memory structure is expected to remain valid for the
 * life of the @FT_Library object.
 *
 * Normally, you would call this function (followed by a call to
 * @FT_Add_Default_Modules or a series of calls to @FT_Add_Module, and a
 * call to @FT_Set_Default_Properties) instead of @FT_Init_FreeType to
 * initialize the FreeType library.
 *
 * Don't use @FT_Done_FreeType but @FT_Done_Library to destroy a library
 * instance.
 *
 * @input:
 * memory ::
 * A handle to the original memory object.
 *
 * @output:
 * alibrary ::
 * A pointer to handle of a new library object.
 *
 * @return:
 * FreeType error code.  0~means success.
 *
 * @note:
 * See the discussion of reference counters in the description of
 * @FT_Reference_Library.
 */
FT_EXPORT(FT_Error)
FT_New_Library(FT_Memory memory, FT_Library *alibrary);


/* *************************************************************************
 *
 * @function:
 * FT_Done_Library
 *
 * @description:
 * Discard a given library object.  This closes all drivers and discards
 * all resource objects.
 *
 * @input:
 * library ::
 * A handle to the target library.
 *
 * @return:
 * FreeType error code.  0~means success.
 *
 * @note:
 * See the discussion of reference counters in the description of
 * @FT_Reference_Library.
 */
FT_EXPORT(FT_Error)
FT_Done_Library(FT_Library library);


/* *************************************************************************
 *
 * @functype:
 * FT_DebugHook_Func
 *
 * @description:
 * A drop-in replacement (or rather a wrapper) for the bytecode or
 * charstring interpreter's main loop function.
 *
 * Its job is essentially
 *
 * - to activate debug mode to enforce single-stepping,
 *
 * - to call the main loop function to interpret the next opcode, and
 *
 * - to show the changed context to the user.
 *
 * An example for such a main loop function is `TT_RunIns` (declared in
 * FreeType's internal header file `src/truetype/ttinterp.h`).
 *
 * Have a look at the source code of the `ttdebug` FreeType demo program
 * for an example of a drop-in replacement.
 *
 * @inout:
 * arg ::
 * A typeless pointer, to be cast to the main loop function's data
 * structure (which depends on the font module).  For TrueType fonts
 * it is bytecode interpreter's execution context, `TT_ExecContext`,
 * which is declared in FreeType's internal header file `tttypes.h`.
 */
typedef FT_Error (*FT_DebugHook_Func)(void *arg);


/* *************************************************************************
 *
 * @enum:
 * FT_DEBUG_HOOK_XXX
 *
 * @description:
 * A list of named debug hook indices.
 *
 * @values:
 * FT_DEBUG_HOOK_TRUETYPE::
 * This hook index identifies the TrueType bytecode debugger.
 */
#define FT_DEBUG_HOOK_TRUETYPE 0


/* *************************************************************************
 *
 * @function:
 * FT_Set_Debug_Hook
 *
 * @description:
 * Set a debug hook function for debugging the interpreter of a font
 * format.
 *
 * While this is a public API function, an application needs access to
 * FreeType's internal header files to do something useful.
 *
 * Have a look at the source code of the `ttdebug` FreeType demo program
 * for an example of its usage.
 *
 * @inout:
 * library ::
 * A handle to the library object.
 *
 * @input:
 * hook_index ::
 * The index of the debug hook.  You should use defined enumeration
 * macros like @FT_DEBUG_HOOK_TRUETYPE.
 *
 * debug_hook ::
 * The function used to debug the interpreter.
 *
 * @note:
 * Currently, four debug hook slots are available, but only one (for the
 * TrueType interpreter) is defined.
 */
FT_EXPORT(void)
FT_Set_Debug_Hook(FT_Library library, FT_UInt hook_index, FT_DebugHook_Func debug_hook);


/* *************************************************************************
 *
 * @function:
 * FT_Add_Default_Modules
 *
 * @description:
 * Add the set of default drivers to a given library object.  This is
 * only useful when you create a library object with @FT_New_Library
 * (usually to plug a custom memory manager).
 *
 * @inout:
 * library ::
 * A handle to a new library object.
 */
FT_EXPORT(void)
FT_Add_Default_Modules(FT_Library library);


/* *************************************************************************
 *
 * @section:
 * truetype_engine
 *
 * @title:
 * The TrueType Engine
 *
 * @abstract:
 * TrueType bytecode support.
 *
 * @description:
 * This section contains a function used to query the level of TrueType
 * bytecode support compiled in this version of the library.
 *
 */


/* *************************************************************************
 *
 * @enum:
 * FT_TrueTypeEngineType
 *
 * @description:
 * A list of values describing which kind of TrueType bytecode engine is
 * implemented in a given FT_Library instance.  It is used by the
 * @FT_Get_TrueType_Engine_Type function.
 *
 * @values:
 * FT_TRUETYPE_ENGINE_TYPE_NONE ::
 * The library doesn't implement any kind of bytecode interpreter.
 *
 * FT_TRUETYPE_ENGINE_TYPE_UNPATENTED ::
 * Deprecated and removed.
 *
 * FT_TRUETYPE_ENGINE_TYPE_PATENTED ::
 * The library implements a bytecode interpreter that covers the full
 * instruction set of the TrueType virtual machine (this was governed
 * by patents until May 2010, hence the name).
 *
 * @since:
 * 2.2
 *
 */
typedef enum FT_TrueTypeEngineType_ {
    FT_TRUETYPE_ENGINE_TYPE_NONE = 0,
    FT_TRUETYPE_ENGINE_TYPE_UNPATENTED,
    FT_TRUETYPE_ENGINE_TYPE_PATENTED

} FT_TrueTypeEngineType;


/* *************************************************************************
 *
 * @function:
 * FT_Get_TrueType_Engine_Type
 *
 * @description:
 * Return an @FT_TrueTypeEngineType value to indicate which level of the
 * TrueType virtual machine a given library instance supports.
 *
 * @input:
 * library ::
 * A library instance.
 *
 * @return:
 * A value indicating which level is supported.
 *
 * @since:
 * 2.2
 *
 */
FT_EXPORT(FT_TrueTypeEngineType)
FT_Get_TrueType_Engine_Type(FT_Library library);

/* */


FT_END_HEADER

#endif /* FTMODAPI_H_ */


/* END */
